Copper tetrathiovanadate (Cu3VS4): a newly emerging electrode for rechargeable aqueous aluminum-ion batteries

We report the electrochemistry of Al3+ ion storage in copper tetrathiovanadate (Cu3VS4) in an aqueous electrolyte for the first time. It is found that Cu3VS4 could deliver an initial discharge capacity of 111 mA h g-1 at a current rate of 0.5 A g-1 and 77 mA h g-1 up to the 300th cycle at 2 A g-1 along with an excellent rate capability. The better electrochemical performance may be attributed to the high theoretical capacity of sulfur and the superior conductivity of copper which allows facile Al3+ ion diffusion in Cu3VS4. The electrochemical mechanism of Al3+ ion storage is also illustrated.